kvm tools: Beautify debug output

1. print mem debug info into debugfd instead guest console
2. always print page table info

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
kvm tools: Fix SDL and VNC by setting vidmode correctly

In commit dfefbe9d4894efc44c39b2041bd667d0dea43eca
kvm tools: allow arch's to provide their own command-line options,
vidmode is not setup correctly.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>